This invention relates to robotic devices and, in particular, to a joint for connecting an end effector to a robotic arm.
In the prior art, a host of different kinds of end effectors have been provided for the many uses of industrial robots. Examples include welding, painting, and article handling via various gripper mechanisms. These end effectors can be attached to a robotic arm by a variety of means. Some are simply directly attached.
A problem arises when end effectors are directly attached to a robotic arm. Any misalignment of the system or anything out of place can cause a collision with the end effector and considerable damage, whether to the end effector, the robotic arm, or some other article.
One approach to the problem is to monitor the current through the servomotors or pumps used to drive the system. The difficulty here is that the rapid motion of the robotic arm requires high torque which, in turn, itself requires high current during acceleration of the arm. Thus, an overcurrent condition becomes difficult to distinguish from normal operations.
Another approach has been to provide various forms of breakaway mechanisms for the arm. In this context, "breakaway" refers to the ability to yield for a predetermined distance upon impact, not that the end effector is separated from the arm.
Joints of the prior art, while providing some breakaway, are limited in the number of axes of motion they can accommodate. In the case of a pneumatic cylinder for example, the joint yields only along the axis of the cylinder. Other, more complicated mechanisms have been provided, but none yield in all axes. Further, even after yielding, they are difficult to restore to their initial alignment with respect to the robotic arm or some other reference.
In view of the foregoing, it is therefore an object of the present invention to provide an improved joint for robotic arms.
Another object of the present invention is to provide a joint capable of yielding in all axes.
A further object of the present invention is to provide a joint which can be restored to its initial alignment easily.